Two-stage two-stroke internal combustion engine



March 15, 1932. w. BRUNNSCHWEILER 1,849,566 I TWO-STAGE TWO-STROKE INTERNAL COMBUSTION ENGINE Filed July 16, 1928' 2 Sheets-Sheet 1 J12 V672 for. W 8 run (Awe/7e,

Mwch 1932- W. BRuNNscHWEaLER 9 15 v TWO-STAGE TWO-STROKE INTERNAL COMBUSTION ENGINE Filed July 16, 1928 2 Sheets-Sheet 2 IN V EN TOR.

A YTTORNEYS.

Patented Mar. 15, 1932 UNITED STA E wmnn BRUNNBGEWTEILER, or swrrznnuuvn Two-arson rwcas'rnoxn INTERNAL connsrion Enema Application filed July 16, 1928, Serial No. 283,058, and in Germany 1111116,!927.

Repeatedly trials have been made to increase the thermal efficiency of the Diesel engine by means of an expansion of the combustion gases nearly approaching the atmospheric 1 pressure, so that the gases partially expan ed in the combustion cylinder are made to act, by way of an'aperture in the cylinder 1 sure crank, being on the same shaft, will pass thru an arc of the same size, but displaced by a certain angle. The gases are exhausted from the low pressure cylinder by means of a. mechanically operated valve, after the high pressure piston has closed again the duct leadin to the low pressure cylinder.

he object of the present invention is to provide a Diesel engine wherein thelow pressure cylinder is fitted with a double acting piston, the inner side of which servesto act,

with its entire, or part of its, surface, as "a preliminary compressor to the new charge of the high pressure cylinder so as toincrease the thermal efliciency of the engine.

In the drawings accompanying the specification and forming part thereof, the invention is shown by way of example.

In the drawin s Fig. 1 is a diagrammatical vertical and longitudinal section of a two stroke internal combustion engine according to the invention Fig. 2 is a similar longitudinal section of another somewhat modified form,

' Fig. 3 is a vertical sectional detail of a practical embodiment of the invention of the:-

type shown in Fig. 2, and I Fig. 4 is a orizontal sectional view through the-arrangement shown in Fig. 3.

According to the invention a low pressure piston 4=is provided in a cylinder ,8 at the V to Fi re 1. -Tlie re ess loss: or heat rough the cooling side of a high pressure piston 3 in a cylinder 1. Both cylinders are connected to a scavenging valve 12'by means of an overflow duct 2 and a scavenging duct 11. In this duct are further arranged a suction valve 9 opening into the outside air, and a ressure valve 10 opening into a scavenging net 11? In the position 'of'pistons shown (Fig. 1) t the low pressure (pro-compressor) cylinder 8 has sucked itself full with atmospheric air by way of the suction valve 9, and the air is compressed by piston 4 on the down stroke and is now passed through pressure valve 10 and duct 11 to the scavenging valve 12, which should open as soon as' the pressure inthe working cylinders connected to each other by duct 2 is reduced to less than the pressure of the air re-compressed in cylinder 8. Now the com ustion gases are scavenged out of the. high pressure cylinder and, after duct 2 has been closed again by piston 3, the high pressure cylinder is charged again by means of the pre-compressor piston 4.

The valve 12 is to be placed as near to cylinder 1 as possible, so that, in the downward stroke of piston 3 a very small part only of the now still incompletely expanded gases may exhaust from cylinder I into the chamber situated above the valve 12. Y

' According to the form shown in Figs. 2 to 4, there are two high pressure cylinders with pistons 14, 14'and their cranks 17 17 are relatively disposed at an angle of 180. They cooperate with a low pressure cylinder, one side being the gas side and the other side the air or compressor side, so that the low pressure crank 20 makes a complete working stroke (are 21) while the high pressure cranks 17, 17 describe the arcs18 and18" (each 90) andpass over the dead center.

*The' low pressure piston thus operates with place quicker than with the type according ansion also results in a water.

doublethe number of strokes of the high pressure pistons per time unit. One low pressure piston is therefore sufiicient fortwo high pressure pistons. A further advantage resides in the fact that re-expansion takes The high pressure piston and the low pressure piston naturally require two separate crank shafts, the number of their strokes being as 1:2; these crank shafts may be connected one to the other by a pair of gearwheels 15, 16. While crank 17 describes the 90 are 18, the low pressure crank 20 describes the are 21, measuring 180; that is the low pressure piston performs its entire working stroke while the two cylinders are connected one to the other, and while the volume of thehigh pressure cylinder is at the end. of its working stroke.

The crank 17 of the second high pressure cylinder 14: is displaced by 180 from the first crank, and is working, therefore, with the low pressure crank in exactly the same alternation as crank 17. The co-operation of piston 14 with piston 13 is not influenced by piston 14, since the latter is closing up the overflow port 19, if the overflow port 19 is open, as is shown in Figs. 2 to 5.

It is of course to be appreciated that in the arrangement shown in Figs. 2 to 4, that two overflow ducts 19, 19 are provided respectively between the two high pressure cylinders 14, 14' and the single lower pressure cylinder 13. A suction valve 9 is provided in the duct 11 while the latter is also fitted with a pressure valve 10. The scavenging duct 11' is also branched as clearly shown in Fig. 5 and the branches are fitted adjacent the cylinders 14, 14 with checking valves 12.

I claim:

1. Two stroke cycle compound internal combustion engine comprising in combination two adjacent high pressure cylinders of small diameter, a piston in each of the said high pressure cylinders, a piston rod for each piston, one common crank shaft for piston rods, a low pressure cylinder arranged laterally between the high pressure cylinders, a double-acting piston dividing the low pressure cylinder into a gas and air side in the low pressure cylinder, the said piston working with a number of strokes which is twice that of the high pressure pistons, a piston rod for the piston of the low pressure cylinder, a crank shaft for this piston rod, a toothed wheel on the crank shaft of the high pressure pistons engaging with a toothed wheel on the crank shaft of the low pressure piston, an overflow duct for expanded gases between each of the high pressure cylinders and the low pressure cylinder, the overflow duct establishing communication between the lower part of the high pressure cylinders and the upper part (gas side) of the low pressure cylinder, a scavenging and charging duct for scavenging and charging air between each hi h pressure cylinder and the compressor si e of the low pressure cylinder, these scavenging and charging ducts extending as a single duct from the air compressor side of the low'pressure cylinder and communicating after being divided into two branches with the lower part of the high pressure cylinders, the mouths of the overflow ducts and I the scavenging and charging ducts in the high sure valves in the scavenging duct adjacent the compressor side of the low pressure cylinder.

2. Two stroke cycle compound internal combustion engine comprising in combination two adjacent high pressure cylinders of small diameter, a piston in each of the said high pressure cylinders, a piston rod for each piston, one commoncrank shaft for piston rods, a low pressure cylinder arranged laterally between the high pressure cylinders, a double-acting piston dividing the low pressure cylinder into a gas and air side in the low pressure cylinder, the said piston working with a number of strokes which is twice that of the high pressure pistons, a piston rod for the piston of the low pressure cylinder, a crank shaft for this piston rod, a toothed wheel on the crank shaft of the high pressure pistons engaging with a toothed wheel on the crank shaft of the low pressure piston, an overflow duct for expanded gases between each of the high pressure cylinders and the low pressure cylinder, the overflow duct establishing communication between the lower part of the high pressure cylinders and the upper part (gas side) of the low pressure cylinder, a scavenging and charging duct for scavenging and charging air between each high pressure cylinder and the compressor side of the low pressure cylinder, these scavenging and charging' ducts extending as a single duct from the air compressor side of the low pressure cylinder and communicating after bein divided into two branches above the mouths of the overflow ducts, the mouths of the overflow ducts and the scavenging and charging ducts in the high pressure cylinders being controlled by the high pressure pistons, a-valve in each ofthe scavenging and charging ducts adjacent the high pressure cylinders and suction and pressure valves in the scavenging duct adjacent the compressor side of the low pressure cylinder.

WERNER BRUNNSOHWEILER. 

